A Practical Treatise on the Diseases of the Eye

William Mackenzie (1791-1868) was the only son of a well-to-do family. Educated originally for the church, he deviated into medicine and was inspired to specialize in the eye by Beer of Vienna. In 1824, he founded the famous Glasgow (Scotland) Eye Infirmary and eventually became one of the foremost ophthalmologists of his era. His book A Practical Treatise on the Diseases of the Eye was the first large and comprehensive textbook of ophthalmology written in the English language. It was published in 1830 and was an immediate, outstanding success. In the original text the 19 chapters are systematically arranged, starting anteriorly with the orbit and lacrimal apparatus and working their way back through the posterior segment. Some of the clinical observations are quite modern in concept but most are limited by the meager knowledge and therapeutic armamentarium of the period. For example, occlusion of the better eye in strabismus is

generally, information of the results of his experience, Dr. Vetch has suffered others to anticipate him in the publication of several observations and points of doctrine, he will not lose the tribute due to him, from any one who will peruse this work with due attention ; even were the evidence wanting that the greater part of the observations alluded to must have been made at periods prior to those of their publication in any literary record, and when, indeed, hardly any knowledge of the general pathology of the eye had been attained. It is extremely gratifying, after having perused this work, to compare the knowledge we now possess of the diseases of the eye with that which was attained by English pathologists before the time of Mr. Sanders. A little empirical information of lj?8 Critical Analysis. inflammation," he says, {i when it does not involve any of the parts immediately subservient to life, is a disease which we are able to command or subdue. Inflammation, more especially as it affects the eye, unaccompanied by constitutional disease, is always to be regarded as susceptible of being conducted to a successful.termination ?but, before such an appellation Can be applied to it with propriety, it is necessary that instances should be adduced of the failure of the means proper for combatting it, when employed in the manner inculcated by the author.
Iii the treatment of inflammation of the eye, he adds, we possess several peculiar advantages, from the singular opportunities we have of observing the, phenomena, and ascertaining the precise limits of the disease, as well as from the uniform nature of the changes incident to its several stages ; and hence a proportional degree of precision ought to be acquired in its management, especially in regard to the attainment of our object by the fittest method, and in adapting the extent of the means employed to the exigency of the case, as well as in regulating them according to their influence locally and on the system in general. ceased to convey any accurate or practical grounds of diStinO4* tion.
[)r. Vetch again restricts the use of the word ophthalmia to the sense above stated : inflammation affecting the eye itself, and cognizable as an external disease, he designates by the appellation of sclerotic inflammation, or ophthalmitis sclerotica, as the term which most distinctly describes the seat and nature of the disease. It might appear that iritis could not be properly comprised by this appellation, but the author, when treating of' this affection, remarks, that, although inflammation may commence in the iris as a primary disorder, while the redness of tlie selerotic coat appears to be secondary or symptomatic,; in either case, the formation of iritis is so blended with a. modified inflammation of the sclerotic coat, that it is impossible, 10 separate the consideration of the one from the other,'1 1 i he following table will present a more particular view of the author's classification of diseases of the eye, which, he says, he has drawn up rather as an index to the observations he has to offer, than as an attempt to introduce a better arrangement f,f the subjects than may have been hitherto proposed. " Ophthalmia, or Conjunctival Inflammation. Sp. I, ? Catarrhal ophthalmia, or ophthalmia mitior, sporadic, endemic, and epidemic, with or without chemosis. " II. Puriform, or ophthalmia purulenta, ophthalmia gravior, the "ppitudo* ophthalmia vera, ophthalmia humida of the ancients, bltphoroblenorrltcea, and ophthalmoblenorrhoea of the German ophthalmologists. by the metastasis of gonorrhoea! inflammation. " e. Ilheumatic, syphilitic, and arthritic. " Ophthalmitis sclcrotica. il Sp. I.?Idiopathic, or corneal. " II.? Iridial, or symptomatic." The author?apparently deeply impressed with the idea that peculiarities in the structure of parts are essentially connected, as causes, with the peculiarities of the phenomena they develop in states of disease,?adduces, in the next place, an anatomieal a?*l physiological account of the membranes which constitute the globe of the eye ; in which he especially considcis the pieeise boundaries, distinctions, and vascular connections, o ie parts in question, as well as exemplifies the jnducnce o t lose eircumstances on the phenomena of several diseases >y some appropriate observations. The cornea, he remarks, a uiou^ i H " The misapplication of lippUudo to a chronic and ^ haps too inveteiate to be now rectified; m its original -> ?
'It acutc stage of ophthalmia." it differs from the proper sclerotica in its minute anatomy, is nevertheless a strict continuation of the latter membrane as far as concerns its vascular connection ; which appears to be a fact of much importance, for, according to Dr. Vetch, " inflammation does not take place in the cornea, and consequently neither suppuration nor ulceration, until inflammatory action has been set up in the vessels of the proper sclerotica, eveji when the exciting cause is applied directly to the substance of the cornea. No symptom of re-action is visible, until that part of the sclerotic coat which is nearest the injured portion of the cornea has put on the appearance of inflammation: on the other hand, idiopathic inflammation once excited in the vessels of the sclerotic coat, invariably tends towards the cornea; and there, in consequence of the more destructible nature of the part, the common consequences of inflammation take place, such as effusion of lymph and ulceration." The very important practical indications which are founded on the above-mentioned facts, will be hereafter considered. The observations which ensue, on iritis, are derived from a further extension of the same views, and are still more interesting than those just cited: it is said that? " The intimate connection formed on the internal surface of the coat with the iris and the ciliary structure, would naturally lead us to expect that the inflammation would have an early tendency to seize upon these parts: attentive observation, however, will prove that, in ordinary or idiopathic inflammation, any apparent affection of the iri^ is more the effect of sympathy than of the actual presence of disease, and that the supervention of iritis is, according to my view of the subject, to be considered as a distinct form of sclerotic inflammation, connected with some idiosyncracy, or morbid diathesis, previously existing in the constitution; and is, for the most part, more insidious in its progress than violent in its symptoms. As, before any degree of acute inflammation can establish itself cither in the cornea or in the iris, a similar action has taken place in the sclcrotic coat, so the farther progress of disease, in either of these parts, continues to be indicated by the greater or less activity of the inflammation in the sclerotic, and to this appearance too much attention cannot be paid.
The feelings of the patient, the stationary appearance of other symptoms, may lull the practitioner into a fatal security, which he will best sivoid by making the condition of the sclcrotic coat the only safe test of the arrested progress of the disease." In further support of those, views, the author remarks, that injury done to the iris by accidental 01* artificial wounds excites no disturbance in the part or uneasiness to the patient, and will eventually heal without any troublesome symptoms, if inflammation dues not appear in the sclerotic coat also ; but in that case the structure of the iris is liable to be destroyed with all the signs of active and acute disease.
;14J Some reflections ensue on the varieties in the character of inflammation dependant on diversities in the structure of the part affected : the violence, as well as the duration of it, the author says, " is, cateris paribus, according to the resistance opposed to the distention of the vessels which have become tho subject of inflammatory action and on this principle he endea, vours to account for the longer duration of active inflammation in the sclerotica than in the conjunctiva. The ordinary course of observation is sufficient to convince us of the truth of the illus-* tration, though we doubt the validity of the arguments adduced support of the above proposition, as they all turn on the notion that the vessels concerned in acute inflammation are in a state of increased action, or, as the author expresses it, of re-t Action on the irritative cause.
There are some other diversities in the general characters of inflammation of the sclerotica and the conjunctiva which are Worthy of attention, as the knowledge of them will aid in the establishment of the diagnosis of the two diseases. In the early stage of conjunctival ophthalmia, the inflammation is most ob-the end or cure of the disease; whilst " the strength and fibre of the patient may be reduced, by abstinence and repeated blood-letting, to the lowest standard, without producing any material benefit, or insuring the organ against the destructive consequence of the farther progress of inflammation." But syncope, produced in the way just mentioned, has no such control over the inflammation which supports itself in the vessels of the sclerotica: in this case, however, the topical abstraction of blood, especially by cupping and leeches, has " sufficient control over the various states and individual symptoms to render any larger bleeding unnecessary." The application of leeches to the conjunctiva of the lower eye-lid, or to the septum nasi, is particularly advised. The exclusion of light from the inflamed eye, is, the author says, c< often more detrimental than useful. The eye becomes more irritable, and less manageable when defended from the access of a moderate degree of light: its exclusion can only be permitted during the very early stage of inflammation. I have treated many thousand cases, and I have never su fie red a shade to be worn." extensively, Dr. Vetch has been led to conclude that a smaller quantity of blood obtained by cupping, is of more real service than a larger quantity obtained in the former way. " The force of the general circulation may also be reduced by the exhibition of antimonials, given in such doses as will keep up a considerable degree of nausea, the direct effect of which in abating inflammation is great, while it produces the further good of forcing the consent of the patient to a due reduction of diet." Cold applications, in the way of wet compresses, and making a solution of opium or hyosciamus the means of applying the cold, are often beneficial. In some cases, the occasional use of fomentations, and the vapour of water and vinegar, produce most alleviation. But, the author adds, " Warm poultices and long-continued fomentations are most especially conducive to the destructive consequences of ophthalmic inflammation,?the relief they may afford being treacherous in the highest possible degree; and so obvious is their tendency to effect relief, by accelerating the destruction of the cornea, that I should consider any patient entitled to recover damages, in whom the disease has terminated unfavourably; whenever it has done so under the application of a poultice." The application of the argentum nitratum, formed into a finely-pointed pencil, to the vessels leading to the cornea, will be found to afford very great relief; and lor this purpose it is sufficient barely to touch the surface of the conjunctiva with the greatest delicacy ; after which the eye is to be immediately washed, by injecting a little tepid water with an clastic gum syringe. The following remarks, from so experienced a practitioner as Dr. Vetch, are particularly interesting ; though the operation to which they relate docs not appear to have been much employed by the generality of practitioners. fection of which, along with the means of subduing the external Ir,flammation, it will be necessary to combine those which insuic the safety of that part. For this purpose, the extract of hyosciamus will be found an advantageous substitute for the belladonna, the effects of the hitter being precarious whenever there isjnuc l 111 ft animation of the proper structure of the eye.
con ,^flailon ?f the c?rnca, resulting from inflammation, is next bee 6 ^ ma^ ta^e P^ace from a similar process having flai 0 Set. UP *n *;'le conjunctiva, as well as from idiopathic inco mat'on ?f its own structure: in the latter case, it often lam*'111011068 ^ aPParent apostemation in the central of the three bv 1032 Part is constituted ; and it may terminate y Proceeding inwards, so as to produce hypopion, or in an exvj r ulcer. The author here adduces an illustration of a re?^?S-^'0n ^at^ before stated : " The first general law ng the morbid changes which take place in the substance c le cornea, is that, until the effect of an injury done to the fla 1C'a lS PI0PaSatet' beyond its circumference, and until in-'nmation is there excited, it retains its natural sensibility, {j Sl,ch inflammation takes place, the ulceration is conducted ii fl.
sei'?us vessels, without producing any visible signs of filiation to the observer, or pain to the patient.'' For c 1 * ^etch's account of the various appearances, progress, and oiisequences, of ulceration of the cornea, we are obliged to rrf.61 t.^le reader to the Avork : we can only notice here his ex-/a llnatlon of the origin of staphyloma, which is new and satishen ulceration has perforated the inner membrane of tnc c?rnea, the aqueous humour flows away externally, and continues to percolate until adhesion of the sides of the opening es place or a small portion of new membrane is formed.
. a second rupture does not soon destroy this reparation of the I'Hernal membrane, it quickly?that is, in a few hours,?pro-Jficts through the external membrane, in the form of a pellucid conical vesicle, the size of which increases in a correspond-Jng ratio with the loss of substance which the ulcer may have occasioned in the middle and outer laminae of the cornea. If le tumor enlarges very much, so as to occupy a considerable Portion of the cornea, it is ordinarily termed staphyloma 5 and 148 Critical Analysis, the same term, Dr. Vetch contends, shfould be given to its more limited formation, for in both cases the process is entirely the same. When staphyloma takes place in the centre of the cornea, and is so small as not to extend to the edge of the iris, the vesicle appears colourless from the first; but when the perforation of the cornea has happened within the limits of the iris, and immediate adhesion of that part with the inner circumference of the ulcer occurs,?constituting what is called procidentia of the iris,?the pupil is drawn to that direction, and the contact of the pigmentum nigrum gives a black hue to the point of adhesion, and communicates the same to the vesicle itself. As the vesicle increases in size, this black hue of it changes into a bluish tinge, whatever may be the colour of the iris. The resemblance which incipient staphyloma bears to the head of the house-fly, has obtained for it the name of myocephalon.
In the treatment of this affection of the cornea, it should be borne in mind that the ulcerative process can only be checked, when it is proceeding to destroy the inner membrane, by those measures which are capable of subduing the inflammation on which the action depends. When the immediate perforation of the inner membrane is threatened, we may with propriety resort to the operation of puncturing the cornea, at a place as remote as possible from the ulcer; the operation being, I conceive," says the author, " fully warranted both by reason and experience." The indication of the ulcer healing is easily seen in the diminished activity of the inflammation, relief from pain, and the clear aspect of the part. The injection of vegetable tepicl astringent infusions, or of milk and water only, may now be used. Next in importance to a diminution of the action on which the ulcer depends, is the removal of any slough formed either on its surface or in the adjoining part of the cornea. This separation may generally be effected by means of the point of a lancet or a couching-needle, round which the slough may be wound in such a manner as to enable the whole mass of it to be withdrawn at once. When it cannot be removed in this way, slight scarifications will cause it to be thrown off very rapidly, in using the instrument, it should be remembered that there probably remains nothing but the third tunic of the cornea to confine the aqueous humour. Sometimes, but always subordinate to the above indications, we may add some topical applications to the ulcer, as a solution ot nitrate of silver, infusion of tobacco, or calomel applied with a camel'shair pencil. The application of caustic to the incipient staphyloma, whether accompanied by procidentia of the iris or not, is another of the secondary measures. The author employs the caustic here in a mode very different from that recom-Dr. Vetch on Diseases of Ihe Eye. 149 landed by Scarpa, who directs it to be applied until a slough f?rmed. Such an application Dr. Vetch considers would be ' a to the success of the remedy : it is quite sufficient that the ^austic barely and instantaneously touches the surface. By ced ? application, repeated daily, the incipient vesicle re-^ es, and the iris, though pointing forwards, is saved from th^ l?ermanent adhesion. If the caustic touches, by accident, e.j 8e ?f the ulcer, or any part but the apex of the projecting th e'often produce much mischief. The diversity in ve-ocies of using this remedy inculcated by Scarpa and Dr. ase .Cl> appears to depend on the former considering the ulcer Je cause of the ophthalmia, and the latter the ophthalmia as the cause of the ulcer. hen staphyloma is of considerable size, there is much dan-Ser of its being burst by slight degrees of external violence; n accident which should, if possible, be avoided, as it is fol-?Tk Senei"ally, by excruciating pain. * he following observations will show the consequences of the more severe cases of this kind.
"Although the staphyloma when completed should extend over wo-thirds of the pupil, that portion of pupil which remains behind "e sound cornea suffers no kind of distortion, and is capable of a small degree of contraction and dilatation, though, for the cause I . ^Ve already noticed, it does not serve the purpose of vision. The ins adheres to the tumor at each side, and that portion of it which remains beneath the sound cornea, whether it includes a portion of the Pupil or not, takes the convexity of the natural cornea, bu^ a sufficiont ^"antity of aqueous fluid remains to prevent the conscquences which v?uld ensue from the actual contact of these parts : the fibres do not ?ufier that distortion which accompanics a more partial procidentia Ir'dis, because, in the latter case, the iris is united to the cenlrc of the P?*rt which the ulcer occupied ; whereas, in a complete staphyloma, a within the base of the tuinor is absorbed, a fact which I have had several opportunities of ascertaining by dissection. The only remains ? the iris I found to be a few widely-separated stria) of pigment on c internal surface of the staphyloma. With a staphyloma occupying |n?rethan two-thirds of the pupil, it is surprising how seldom the rp"s's displaced by falling forward into the cavity of the staphyloma, uc iris adhering at each side of the tumor seems sufficient to retain ls body in its place, and, although the anterior chamber is wholly ?"'iterated, the secretion of the aqueous humour is greater than in the natural state of the part." T lie treatment of this affection has been regarded chiefly with a view to lessen the unsightliness of the tumor, for which Purpose its removal, by cutting off a portion of it, has been recommended by Scarpa ; whose own evidence, however, warns t-,le reader of the severe inflammation and suppuration which are likely to ensue from the operation. 150 Critical Analysis, " There is, however, a much stronger objection to the operation/' says Dr. Vetch,44 in the fact, that an eye affected with staphylomas is not in so perfectly a hopeless state as it is but reasonable to suppose must be the case after such an operation as the one alluded to. Nature attempts the cure in every case, and in many brings it within the power of art to complete the success of her effort. While the process by which the thin membrane is converted into a white thick coriaceous substance is going on, the repeated rupturing of the parts which have riot yet suffered (his conversion diminishes the tumor, which, finally, contracts and subsides to the natural shape of the cornea, leaving an indelible leucoma over the place which it occupicd. An artificial pupil may then be formed with the same favourable prospect of success as in any other case of obliteration of the pupil from leucoma of the cornea. 44 The evacuation of this humour is often required to relieve the sudden and violent attacks of pain which its distention excites in the eye, or in distant parts of the head. Though I never measured the quantity of water which escapes, 1 think, in some cases, it must have amounted to two drachms. The incision heals immediately, and in a few hours the water is re-produced. I object, therefore, both to the removal of the apes of the tumor, as recommended by Scarpa, as painful and hazardous, besides being destructive of all chancc of recovery ; and to the puncturing of the tumor, as an endless operation, from which no^permanent effect takes place. I have had recourse, ?with success, to caustic, and to the introduction of a seton in order to accomplish the gradual diminution of the tumor, and to bring the eye into that state where an artificial pupil may be made : at all events, to destroy the deformity of the projection, without the risk of a severe attack of inflammation and suppuration of the eye-ball." The cornea is liable to a very considerable alteration of its shape, without any evident change of its structure, by which it assumes the form of a cone. 44 In all my attempts to restore the natural convexity of the part," says the author, 44 I have failed: evacuating the aqueous humour, removing the lens, and the application of long-continued pressure, have not been attended, as far as 1. know, with any improvement of vision."" Sometimes the cornea suffers a loss of substance, by a process of absorption different from that which takes place when that action is combined with the more obvious signs of inflammation ; the result of which is a pellucid dimple. It seems to depend on a removal of the middle lamina of the cornea. Jt is riot productive of much inconveniencej and, when formed, often remains stationary for a very long period.
Opacity of the cornea, consequent on primary conjunctival inflammation, is next treated of. The surface of the eye sometimes presents, from the cause just designated, a,rough or granulated appearance, with a varicose state of the external vessels and a secretion of puriform matter ?, and universal opa-Dr. Vetch oil Diseases of the Eye. ? 151 city of the cornea takes place from the irritation produced by the disease of the conjunctiva. The lining of the palpebrae, especially that of the upper, partakes of the disease, and presents a remarkably villous appearance in the first stage of it, which is succeeded in proccss of time by deeply-sulcated, hard, pr warty, granulations. We must refer the reader to the work itself for a more particular history of this affection. "In the whole class of diseases of the eye,5' says the author, " and. jts appendages, there is no one affection so distinctly pointed out, and its treatment so uniformly described, by all ancient authors, as this state of the linings of the palpebrne, termed by the Greek writers* trachoma and sycosis, from the granular appearance of the surface; by the Latins, scabies and scabrities palpebrarum ; and by the Arabians, scbel. + " So completely, however, had such knowledge been overlooked in this country, that the real nature, as well as the cure, of the complaint may be considered as a recent acquisition ; and we have seen the most unworthy claims set up as to the merit of introducing both the ?ne and the other. The use of actual cautery, excision, and friction, for the purposes of curing the diseased state of the eye-lids, may bo traced back to the writings of Hippocrates, and these measures seem to have been employed both separately and combined. The destruction of the granulations by friction, appears to have been the practice more generally followed in former times. The adoption of the more preferable mode of practice, by the application of escharotic agents, may, ^ think, with justice be conceded to Mons. De St. Ives: this author, whom I have not consulted till lately with that attention to which lie is so well entitled, appears, in his own country, and at the distance of exactly one hundred years, to have performed a similar service to surgery, which, in our time, has been conferred upon it by the late Mr.
Saunders, whose high qualifications ;ind talents have now so successfully established the cultivation of ophthalmological science among us." Dr. Vetch is decidedly adverse to the treatment of this affection by excision, preferring, as above shown, the application of escharotics. et After giving a fair trial to a great variety of this elass of medicines," he says, " applied to the surface of the Upper eye-lid in the form of ointment, I was led to trust to their application in substance alone, by which the treatment became so decidedly successful as to enable me to calculate .with cei-* Trachoma asperitas intra palpcbram, est Iinjus intentio, nt vehit incismas "abeat sycosis, a ficus similitndine vocatur, ubi vero diu duravit, et caliuni contraxit tyosis, id est callositas nominatur, si non his cadet ioversam palpebram per puiuicem rademus ant per sepias testani, aut fici folia, aut etiaui pet jus in Uientum blexharoxt/slon ah hac opera appcllatuin. Critical Analysis, tainty on the cure of the disease, when not opposed by mora) obstacles which no means could control." But, notwithstanding the evidence adduced by the author, as long since as the year 1806, of the superior merit of this mode of treatment, that by excision has been established in the practice of the army: " but," Dr. Vetch asserts, " it never could have received the trial which has been given to it, if left to the unbiassed decision of the profession; and, when time shall have removed all personal consideration, the mode of practice which succeeded with me will maintain its reputation, when that by excision will be left without an adherent." The following recapitulation will show the grounds for the foregoing decision, at the same time that it will point out, more particularly than we have yet done, the mode of employing-the means of cure here recommended. " First, that, of itself, the operation, however frequently repeated, is unequal to the cure of opaque cornea; while, on the other hand, the treatment I adopted in the disease does not require the aid of an operation in one case out of fifty. " Secondly, that the operation, besides being in itself very painful, requires to be indefinitely repeated, and is often followed by inflamma-plcte aversion of the palpebral; nor will I yield the evidence of my own sense and experience on this point to any conjectural reasoning whatever. The treatment of this affection forms but one feature of a disease which, at the time that I met with it, was new to the profession in this country ; and, although the practice proved successful to the utmost possible degree, it has been condemned without inquiry and without appeal, and in a quarter where professional discussion cannot be entertained.
(l The whole power of high and official patronage has been employed ensuro the success of the operation for removing the grauulation of *he palpebral by the knife ; the failures have been concealed by every possible subterfuge. Nature, however, has proved her superiority ; ar'd it is now generally known that the operation, while it has been highly injurious in some cases, has only proved successful when aided ljy those applications which it was introduced to supersede ; and this Success has been so limited, as to prove that their use is not yet properly understood where the greatest pretensions have been advanced.
It will sometimes be advisable to take blood from the temples hy cupping, to remove increased action of the vessels of the sclerotic coat, (one of the indications in the treatment,) at the same time that the measures are employed for the cuie of the affection of the palpebral linings. The escharotics, for the latter purpose, should be pointed in the form of a pencil, and fixed in a port-crayon, as already mentioned ; and they are to u.c appliecl, not, as some iiave conceived, so as to produce a s ?ugh over the whole surface, but with great delicacy, aud in ? m'dnY points only as will produce a gradual change in the Condition and disposition of the part. It is not necessary at all Jfnes that the escharotic should be applied to every part of the ('seased surface, for, when a healthy action re-commences, it soon becomes general. As long as any purulency remains, the a Jove applications will be much aided by the daily use of tfie UndiiuteC| liquor plumbi acetalis, applied by means of a camel'slai? pencil. When the disease resists these remedies, and the surface becomes hard and warty, the author has had recourse to inely levigated verdigris or burnt alum, and sometimes the kali Purum, applied in the way just mentioned ; taking care that l y ai"e washed off by means of an elastic-gum syringe before ie eye lid is ieverted. Ail the substances above enumerated, Avhen used in the way described, are to be here regarded, the ai,thor says, as acting, not as escharotics, but as astringents.
??e practitioners have attempted to aid their efficacy by astringent washes ; but these are always injurious, as they act *l so on parts which should be preserved from their irritative aSeucy. The solid substances can be applied with precision to 3(3 points only on which it is desirable that their influence should be exerted. The liquor plumbi acetatis Avas usually No. 264.
x J 54 Critical Analysis. employed by the author in the worst stage of the disease, arrcJ was changed, as the cure proceeded, for a solution of alum, applied by a camel's-hair pencil.
The excision of a portion of the conjunctiva immediately surrounding the cornea, recommended by Scarpa, was employed in the treatment of the cases in the military hospital, under the direction of Dr. Vetch, so as to give it a fair trial; but, it is said, without any good effect, excepting in cases of great relaxation of the membrane covering the eye. The division or excision of the large varicose vessels which usually unite towards the external angle of the eye, has little or no effect, as new vessels immediately appear in the room of those removed by the operation, and the discharge of their contents does not compensate for the excitement which their excision occasions.
The prognosis in this disease is always favourable ; and the more completely the cornea has become soft and opake, the more easily it is cured ; though, if the patient's age is much above twenty, he is for some time liable to a relapse.
The fundamental points of the author's pathology of ophthalmitis iritica, or, as it has been commonly termed, iritis, have been already stated in this article, and we could add but little to what we have adduced on this subject without entering into details for which it is more proper that the reader should be referred to the work. Many observations are here brought forward in confirmation of the author's proposition respecting the insensibility of the iris, even when suffering inflammation.

156
Critical Analysis. as the disease extends itself more and more to the iris, this symptom, instead of increasing, sensibly diminishes. Flashes of light are often supposed to be seen, when the irritation of ,the iris is great; for the same reason, that noises are perceived in the ear, when the organ of hearing is irritated.
In the worst cases of this disease, besides the lesions already mentioned, such a change in the structure of the sclerotic coat is liable to happen, that it can no longer preserve its regular spherical form, but suffers a partial projection in some part more than another, known by the name of staphyloma sclerotica. Hypopion, cataract, and amaurosis, are other occasional consequences of sclerotic iritis; the whole of which, as well as the more ordinary progress and consequences of this disease, are minutely and perspicuously described by the author, with all the originality of manner which marks the rest of the work.
The treatment of this affection should not materially vary from that proper for ophthalmitis externa, except in the use of mercury and belladonna, or hyosciamus, from the commencement ; and, from the importance of the organ here affected, in the extreme vigilance and activity necessary in the employment of local blood-letting. " A small quantity of mercurial ointment with opium rubbed into the eye-lid and temple, night and morning, seems," Dr. Vetch says, <? to have a specific agency in arresting the progress of the disease in the iris. The same may be said of the local nse of stramonium and hyosciamus, -which not only prevent the contraction of the pupil, but, after the removal of inflammation, appear very evidently to increase the mobility of the iris, by disengaging it from the adhesions it has formed with the capsule of the lens." Dc. Vetch concurs with former experienced writers, in stating that, although the disease has occurred during a course of mercury, Ave may renew the exhibition of this medicine with safety and advantage. The local application of it, in the way just designated, will be sufficient when the iritis is not connected with syphilis, in which case it should be employed in a more effective manner : the rest of the treatment is not to vary from that which is proper when the disease arises from other causes.
The recurrence or increase of pain, it seems important to remark, is always regarded by the author as an indisputable and unequivocal symptom of augmented inflammation.
Lenticillar and capsular inflammation, and its consequence, cataract, are next treated on. Besides the inflammation from which cataract most frequently originates, the lens is subject to a more acute and destructive form of inflammation, which, in contra-distinction to that producing the more gradual loss of transparency terminating in the lenticular and capsular cataract, may be termed Icntitis.
Cataract exemplifies the adhesive fifth, at first cataract obstructs the vision of objects directly opposite to the eye, but, when viewed sideways and in a moderate light, they are discerned with tolerable clearness; sixth, dioptric glasses aid the vision of cataract patients, so long as the cloudliness behind the pupH ls inconsiderable: the flame of a candle appears to an eye in which cataract is forming, to be surrounded by a whitish circle or vapour, yhich appears broader the farther the patient removes from the light: if the cataract be completely formed, the patient can no longer see the flame, and can merely say where it is. Lastly, incipient cataract does pot influence the mobility of the iris; if, at last, its movements are impaired, the complaint is by that time sufficiently obvious. On the other hand, the appearances which characterize the formation of amaurosis, are the great depth at which the cloudiness appears behind the pupil on looking at the eye sideways; from the cloudiness appearing somewhat concave; from its colour being more of a greenish or reddish hue. The diminution of vision bears no proportion to any perceptible cloudiness; the pupil is more or less expanded, the iris little or not at all movable; the pupillary border angular, and the pupil not perfectly circular; the cornea loses its natural and healthy aspect. In incipient amaurosis, there is also a remarkable increase or diminution of vision, not affected, as in cataract, by the degree of light or expansion of the pupil, but depending on physical and moral causes, affecting the sensibility of the individual: violent emotions of mind often giving a temporary increase of vision ; while it is evidently diminished by long fasting, restless nights, great anguish, sudden fright, or excessive venery : under the operation of such causes, incipient amaurosis often terminates in permanent blindness, lo tho amaurotic patient, the flame of a candle appears as if involved in a mist, but, unlike the white cloud already described, exhibits, as well as the flame itself, the colours of a rainbow. Glasses are of no use to the amaurotic patient, and he distinguishes objects at the side with as much difficu 1 ty as those dircctly opposite to the eye. ' All the species and complications of cataract are then cons!-, dered ; for an account of which it is absolutely necessary that we refer to the work. The general principles foi the treatment of the two kinds of cataract, independent of the operations for 158 Critical Analysis, them, mcist be manifest on the slightest consideration on the pathology of those affections : the greatest difficulty generally consists in determining the influence of local or of constitutional exciting causes. To these remarks we may add the citation of the following paragraph: " Practitioners, who give themselves little trouble in investigating the particular nature of cataract, too often satisfy themselves and their patients by telling them to do nothing, but wait till the cataract is ripe or fully formed,?that is, until they are deprived of all useful vision. It is obvious, however, that in all cases depending upon inflammation, however slow and however obscure, it is the duty of the practitioner to prevent the further formation of the disease, by the means directed to subdue such diseased action ; and, generally speaking, the same line of treatment which has been recommended for iritis, is equally applicable to the early stage of capsular inflammation ; and it will be greatly aided by the use of setons or issues and rubefacients/' Amaurosis is the next subject of the author's observations, and it furnishes him with an occasion for adducing some forcible illustrations of a pathological principle, apparently true, which he seems particularly desirous to establish, and the knowledge of which is of great importance in regard to practice. He had already remarked, on speaking of iritis, that inflammation of the nerves of the senses properly is not accompanied with increased sensibility, as is the case with the other nerves; but, on the contrary, with a diminution of their proper sensibility : hence, inflammation, or increased vascularity of the retina, instead of being attended with increased power of perception of light, is productive of amaurosis. It is common to hear this affection spoken of as a state of debility, or want of excitement of the optic nerve, and not of inflammation, on the analogy that irritation of nerves in general is accompanied with increased sensibility; but, Dr. Vetch remarks, it will be found that the causes of amaurosis are often those which are productive of increased determination of blood to the head, and to the eyes especially ; and he, by a series of arguments, shows that amaurotic blindness may be the consequence of direct inflammation of the retina, or of the vascular structure on which it rests. But, whilst he establishes this point, he takes care also to point out that it may in some cases arise from " local debility influenced by repletion of the system, obstructed circulation," and from " actual loss of power, from the natural decay of age or protracted debility." He however considers that, excepting when it occurs at a very advanced period of life, it is almost always formed out of some pre-existing disease. After the preliminary pathological reflections above designated, the author gives a very perspicuous analysis of the symptoms, with an account of the disordered sensual phenomena, and a description of the va-influence, the .author adverts to the ophthalmia of Egypt,?a country which, of all others, seems to be the most favourable to the production of inflammation of the conjunctiva; and tlie causes of which he, in the first place, endeavours to determine.
He shows, satisfactorily, that it is not, as it has commonly been supposed, on the sands, or the influence of the drying winds, that it depends; but on the extreme humidity and relative coldness of the atmosphere during the night. An opinion very early published by Dr. Vetch, in the fourth volume of the Edinburgh Medical and Surgical Journal, and in which Assalini and Mr. Power coincide with him ; though each of them seems to have been led to it, nearly at the same time, by their own observations. Some remarks ensue on the catarrhal ophthalmia of Europe. The author applies the term catarrhal rather than purulent to the ordinary ophthalmia of temperate climates from atmospheric influence, although the matter formed u may, and does," he says, It happens, unfortunate^, that the author has not made it evident whether the experiment of the hospital assistant was made with the matter of a gonorrhoea aflecting himself or another person ; but we must, with almost absolute confidence, suppose it were from gonorrhoea affecting himself, (from the nature of the context, and Dr. Vctch in another place shows that ophthalmia may be produced by the contact of gonorrhoeal matter;) and, if so, it might appear that the conclusion immediately following the account of it, is .not quite satisfactorily established, because the gonorrhoeal ophthalmia ordinarily witnessed may arise from the matter of another individual coming in contact with the eye of the patient, and probably at the same time that the gonorrhoeal infection has been received. Dr. Vetch had previously opposed this view of the subject, by the statement that gonorrhoeal ophthalmia occurs too frequently to admit of the probability of its correctness.
In support of the above-mentioned views, Dr. Vetch brings forward a case where the ophthalmic affection accompanying a gonorrhoea was accompanied also with an attack of rheumatism in other parts, and the ophthalmia, as it generally is in analogous cases, was sclerotic, not conjunctival, inflammation; whilst that produced by inoculation affects only the conjunctiva.
The inflammation of tiie sclerotica is very frequently, in the cases under especial consideration, communicated to the conjunctiva ; and so is decidedly idiopathic inflammation of the sclerotica from other causes. It is but seldom, Dr. Vetch believes, that " the gonorrhoeal action is translated to the conjunctiva, without attack ins: the sclerotic coat also." These iacts strongly favour thrathor's opinion of the nature of gonorrhoeal ophthalmia as it most ordinarily occurs; and several others, which our limits will not permit us to lioticc, are brought forward by him in its support.
The author says but little respecting the treatment of gonorrhoeal sclerotic inflammation; but we may suppose that he does